1 /*
   2  * Copyright (c) 2003, 2004, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /* @test
  25  * @bug 4546734 5007612
  26  * @summary Test StringBuffer.trimToSize
  27  * @key randomness
  28  */
  29 
  30 import java.util.Random;
  31 
  32 public class Trim {
  33     private static Random generator = new Random();
  34 
  35     public static void main(String[] args) throws Exception {
  36         bash();
  37         //capacityCheck();
  38     }
  39 
  40     // Make sure trimToSize is safe to use; it should never cause an
  41     // exception or mutation
  42     private static void bash() throws Exception {
  43         for (int i=0; i<1000; i++) {
  44             StringBuffer sb1 = generateTestBuffer(0, 100);
  45             StringBuffer sb2 = new StringBuffer(sb1);
  46             sb1.trimToSize();
  47             if (!sb1.toString().equals(sb2.toString()))
  48                 throw new RuntimeException(
  49                     "trim mutated stringbuffer contents");
  50             // Append a random sb
  51             StringBuffer sb3 = generateTestBuffer(0, 100);
  52             sb1.append(sb3);
  53             sb2.append(sb3);
  54             if (generator.nextInt(2) == 0)
  55                 sb1.trimToSize();
  56             else
  57                 sb2.trimToSize();
  58             if (!sb1.toString().equals(sb2.toString()))
  59                 throw new RuntimeException(
  60                     "trim mutated stringbuffer contents");
  61             // Append sb with lots of extra space
  62             sb3 = new StringBuffer(100);
  63             sb3.append("a");
  64             sb1.append(sb3);
  65             sb2.append(sb3);
  66             if (generator.nextInt(2) == 0)
  67                 sb1.trimToSize();
  68             else
  69                 sb2.trimToSize();
  70             if (!sb1.toString().equals(sb2.toString()))
  71                 throw new RuntimeException(
  72                     "trim mutated stringbuffer contents");
  73         }
  74     }
  75 
  76     // This test gives some assurance that trimToSize is working but
  77     // it should not be part of an automated run, and a failure here
  78     // is not against spec; this method is provided simply to be run
  79     // by hand and assure the engineer that it is working. The test
  80     // may stop working at some time in the future depending on
  81     // how String and StringBuffer are implemented because it depends
  82     // upon the capacity method.
  83     private static void capacityCheck() {
  84         for (int i=0; i<100; i++) {
  85             int sizeNeeded = generator.nextInt(1000)+1;
  86             int sizeExtra = generator.nextInt(100) + 1;
  87             StringBuffer sb = new StringBuffer(sizeNeeded + sizeExtra);
  88             StringBuffer sb2 = generateTestBuffer(sizeNeeded, sizeNeeded);
  89             if (sb2.length() != sizeNeeded)
  90                 throw new RuntimeException("sb generated incorrectly");
  91             sb.append(sb2);
  92             int oldCapacity = sb.capacity();
  93             sb.trimToSize();
  94             int newCapacity = sb.capacity();
  95             if (oldCapacity == newCapacity)
  96                 throw new RuntimeException("trim failed");
  97         }
  98     }
  99 
 100     private static int getRandomIndex(int constraint1, int constraint2) {
 101         int range = constraint2 - constraint1;
 102         if (range <= 0)
 103             return constraint1;
 104         int x = generator.nextInt(range);
 105         return constraint1 + x;
 106     }
 107 
 108     private static StringBuffer generateTestBuffer(int min, int max) {
 109         StringBuffer aNewStringBuffer = new StringBuffer();
 110         int aNewLength = getRandomIndex(min, max);
 111         for(int y=0; y<aNewLength; y++) {
 112             int achar = generator.nextInt(30)+30;
 113             char test = (char)(achar);
 114             aNewStringBuffer.append(test);
 115         }
 116         return aNewStringBuffer;
 117     }
 118 
 119 }